Technology, geometry key to completing Seattle's Highway 99 project

05/16/2013 | KING-TV (Seattle) · Seattle Times, The

About 130 workers at FBS Encon Precast in Washington's Pierce County are manufacturing 14,000 concrete components for the $2 billion Highway 99 tunnel project on the Seattle waterfront being built by a Dragados/Tutor-Perini joint venture. Each tunnel ring is made up of nine arcs and a smaller keystone, and despite there being only one ring size, the 1.7-mile tube will be able to curve "because each ring is 2.65 inches narrower on the keystone side than the opposite side." Bertha, the boring machine that will excavate the tunnel beneath the old Alaskan Way Viaduct, will begin digging the tunnel in July.

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KING-TV (Seattle) · Seattle Times, The

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